Solar Thermal or Photovoltaic Cooling? - IEA SHCtask48.iea-shc.org/Data/Sites/6/documents/events/intersolar2012... · Solar Thermal or Photovoltaic Cooling? ... Cooling tower Compression

Intersolar Europe 2012 Prof. Dr. Ursula Eicker

Folie 1

Solar Thermal or Photovoltaic Cooling?

Prof. Dr. habil. Ursula Eicker

Research center sustainable energy technologies – zafh.net

University of Applied Sciences Stuttgart

Collector field


Folie 2

Compression

cooling machine

Cold

storage

tank

Public grid

electricity

PV modules

Solar cooling systems


Folie 3

zafh.net

PV Module Prices Development 2009 - 2011

Source: www.solarserver.de


Folie 4

Methodology: Simulation studies in planning phase

- Location- Building characteristics- Thermal solar system

characteristics

Comparison of results:- Energy performance

- Costs

Thermal solar cooling system

(absorption chiller)

TRNSYSProduction of annual

load and weather data

TRANSOL INSEL

Reference system (compression chiller)

Electrical solar coolins system

(compression chiller + PV modules )


Folie 5

Small office building European conditions

DHW

Solar collector

field

Heat exchanger

Solar storage tank

Cooling tower

Compression chiller

(back up)

Absorption chiller Cold

storage tank

Primary loop Secondaryloop

Auxiliary storage tank

Auxiliary gas heater

Cold distribution

loop

Task 25 Office building in three climates (Palermo, Madrid, Stuttgart)

• Absorption 35 kW (COP = 0.7) versus Compression 30 to 50 kW

• Backup CCM 10kW (COP= 3.5)

• Flat plate/vacuum tube collectors – Monocrystalline Silicon

• Heat storage (5m³)

• Cold storage (1m³)

• Wet cooling tower


Folie 6

Compressor performance model

2

4

6

8

10

12

14

16

2.00

2.50

3.00

3.50

4.00

4.50

5.00

5.50

6.00

4 6 8 10

Pe

lec

(kW

)

CO

P

Tout evaporator (°C)

40 kW COP (Tin cond = 25°C)

COP (Tin cond =30°C)



COP sim (Tin cond = 25°C)

COP sim (Tin cond =30°C)



Pel (Tin cond = 25°C)

Pel (Tin cond =30°C)



Pel sim (Tin cond = 25°C)

Pel sim (Tin cond =30°C)




Folie 7

Cooling loads

CASE City Uwall

(W/m²

K)

Intern

al

loads

Sun

Protec-

tion

Annual

cooling

load

(kWh/m²)

Annual

heating

load

(kWh/m²)

Maximum

cooling load

(W/m²)

Case 1 Palermo 1.1 low yes 46 18 38.0

Case 2 Palermo 0.41 low yes 61 0 31.9

Case 3 Palermo 1.1 high no 94 2 54.1

Case 4 Palermo 0.41 high no 141 0 39.4

Case 5 Madrid 0.66 low yes 34 11 34.4

Case 6 Madrid 0.41 low yes 36 5 32.6

Case 7 Madrid 0.66 high no 88 0 35.6

Case 8 Madrid 0.41 high no 97 0 34.2

Case 9 Stuttgart 1.1 low yes 8 56 23.8

Case 10 Stuttgart 0.41 low yes 17 20 22.6

Case 11 Stuttgart 1.1 high no 31 25 29.8

Case 12 Stuttgart 0.41 high no 54 2 30.2


Folie 8

Solar fraction for PV and ST cooling


Folie 9

0

2

4

6

8

10

12

14

16

0 20 40 60 80 100 120 140 160

ele

ctr

ica

l C

OP

Annual cooling load (kW/m²)

Palermo (Uwall =1.1 W/Km²) Palermo (Uwall =0.41 W/Km²)Madrid (Uwall =0.66 W/Km²) Madrid (Uwall =0.41 W/Km²)Stuttgart (Uwall =1.1 W/Km²) Stuttgart (Uwall =0.41 W/Km²)Pal PV Mad PVStut PV

Stuttgart Madrid Palermo

Thermal solar system

PV solar system

Electrical energy requirement


Folie 10

Reduction of auxiliary energy by optimised control


Folie 11

Primary energy savings for cooling


Folie 12

Cost comparison


Folie 13

Total annual costs


Folie 14

Cost of cooling production

CASE Photovoltaic cooling system Thermal solar cooling system PV Export Grid Feed in tariff Heat use Heat price

A No - No -

B yes Germany 0.2455 €/kWh

Italy 0.2085 €/kWh

Spain 0.1855 €/kWh

Yes Germany 0.0572 €/kWh



C yes Germany 0.42 €/kWh

Italy 0.33 €/kWh

Spain 0.4 €/kWh

-

D yes Germany 0.19 €/kWh



Yes Germany 0.114 €/kWh

Italy 0.108 €/kWh

Spain 0.101 €/kWh


Folie 15

Design project Baden Württemberg State Ministry

Motivation:

strong summer overheating, no night ventilation

Renewable heat law: 15 % solar thermal for

heating and cooling (of public buildings)

Result:

25-50% solar fraction

with thermal cooling

system


Folie 16

Recommendation for small systems

PV most cost effective – but low solar fractions of 20-30%

Solar thermal cooling for base load to reduce costs

Peak loads with electric compression + PV with grid feed in


Folie 17

Large solar cooling systems for mediterranean climates

Cairo office building

15100 m² surface

52 W/m² cooling load

130 kWh/m² cooling

energy demand


Folie 18 1

8

Case Chiller

Type Cooling Capacity

Collector

Type Collector Area Storage Tank

brut aperture hot cold

Case 1 Single

Effect 422 kW Vacuum

Tube 2025 m² 1350 m² 20 m³ 10 m³

Case 2 Double

Effect 500 kW Linear

Fresnel 2050 m² 1320 m² 20 m³ 10 m³

Case 3 Triple

Effect 563 kW Linear

Fresnel 1280 m² 800 m² -- m³ 10 m³

Kawasaki Sigma, triple effect

Ace CF01-10-0001

Shuangliang, double effect

500 kW

THERMAX, single effect

ProChill LT12C

Comparison of large multi-effect systems


Folie 19

Absorption Cooling Fraction and Solar System Efficiency

37%

91%93%

40%

31%

27%

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Single effect ACM + vacuum tube collectors

Double effect ACM + Fresnel collectors

Triple effect ACM + Fresnel collectors

Sola

r syste

m e

ffic

iency /

%

AC

M fra

ction /

%

ACM fraction Solar system efficiency


Folie 20

Heating Energy Consumption and Average COPth

1050

792

469

577

534

0.70

1.31

1.83

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0

200

400

600

800

1000

1200

1400

Single effect ACM +

vacuum tube collectors

Double effect ACM +

Fresnel collectors

Triple effect ACM +

Fresnel collectors

CO

Pth

/ -

Heating e

nerg

y c

onsum

ption /

MW

h a

-1

Qh_solar Qh_additional COPth


Folie 21

Primary Energy Efficiency

183

443 462

12401443

692 6401194

176128

1900

1.431.50

1.60 1.59

1.37

1.04

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0

200

400

600

800

1000

1200

1400

1600

1800

2000

Single effect ACM +

vacuum tube collectors

Double effect ACM + Fresnel

collectors

Triple effect ACM + Fresnel

collectors

CCM with PV collectors,

grid as ideal storage

CCM with PV collectors, electricity

directly used

Reference system with compression chiller only

Pri

ma

ry e

ne

rgy r

atio

PE

R /

-

Pri

ma

ry e

ne

rgy c

on

su

mp

tio

n /

MW

h a

-1

Electricity Additional heating Additional cooling PER


Folie 22

System Costs Including Installation and Integration T

ota

l syste

m c

osts

/ €

Specific

syste

m c

osts

/ € p

er

kW

coolin

g p

ow

er

2 242

2 626

2 040

1 102 1 102

381

0

500

1 000

1 500

2 000

2 500

3 000

0 €

250 000 €

500 000 €

750 000 €

1 000 000 €

1 250 000 €

1 500 000 €

1E 2E 3E CCM_PV CCM_PV_dir CCM_ref.

Installation and integration

Piping

hot and cold storage

Collector / PV

Chiller and heat rejection

Specific system costs


Folie 23

Overall Cooling Costs / Office Building in Cairo, Egypt

Prices: Gas = 0.0174 €/kWh Electricity = 0.062 €/kWh Water = 1.6 € / m³

Source: www.worldtribune.com Inflation rate = 5.6%/a Discount rate = 6%/a

78

92

82

6566

51

0

10

20

30

40

50

60

70

80

90

100

- €

20 000 €

40 000 €

60 000 €

80 000 €

100 000 €

120 000 €

140 000 €

160 000 €

180 000 €

200 000 €


Cool

ing

cost

s [€/

MW

h]

Ann

ual C

osts

[€/a

]

Operational cost annuity

System cost annuity

Cooling costs


Folie 24

Overall Cooling Costs / Office Building in Cyprus

Prices: Gas = 0.101 €/kWh Electricity = 0.230 €/kWh Water = 4.0 € / m³

Inflation rate = 5.6%/a Discount rate = 6%/a

161

187

171

131

143148

0

25

50

75

100

125

150

175

200

- €

50 000 €

100 000 €

150 000 €

200 000 €

250 000 €

300 000 €

350 000 €

400 000 €


Spec

ific

cool

ing

cost

s [€/

MW

h]

Ann

ual c

oolin

g co

sts [€/

a]

Operational cost annuity

System cost annuity

Cooling costs


Folie 25

Conclusion

Solar thermal and photovoltaic cooling allows for primary energy savings of 30 to 50% in typical office building projects

Good partial load control is important for primary energy savings

For reduced feed in tariffs and increasing heat costs the total costs of PV and solar thermal cooling are comparable

For long operating hours solar cooling is competitive with conventional cooling

The primary energy efficiency of solar thermal cooling is comparable or higher than photovoltaic cooling, especially when double or triple effect chillers are used

Documents

Solar Thermal or Photovoltaic Cooling? - IEA SHCtask48.iea-shc.org/Data/Sites/6/documents/events/intersolar2012... · Solar Thermal or Photovoltaic Cooling? ... Cooling tower Compression